auto-save-include-big-deletions

[Chong Yidong]

To handle the rmail auto-save problem in a cleaner way, I propose the
following change to fileio.c, adding auto-save-include-big-deletions.
If this variable is non-nil, that disables the turning off of auto-save
after big deletions.  (Rmail can then bind this locally to t.)

Any objections?

*** emacs/src/fileio.c.~1.654.2.2.~     2009-07-07 18:45:24.000000000 -0400
--- emacs/src/fileio.c  2009-07-21 12:17:36.000000000 -0400
***************
*** 193,198 ****
--- 193,201 ----
  /* Whether or not files are auto-saved into themselves.  */
  Lisp_Object Vauto_save_visited_file_name;
  
+ /* Whether or not to continue auto-saving after a large deletion.  */
+ Lisp_Object Vauto_save_include_big_deletions;
+ 
  /* On NT, specifies the directory separator character, used (eg.) when
     expanding file names.  This can be bound to / or \. */
  Lisp_Object Vdirectory_sep_char;
***************
*** 5321,5328 ****
                && EMACS_SECS (before_time) - b->auto_save_failure_time < 1200)
              continue;
  
!           if ((XFASTINT (b->save_length) * 10
!                > (BUF_Z (b) - BUF_BEG (b)) * 13)
                /* A short file is likely to change a large fraction;
                   spare the user annoying messages.  */
                && XFASTINT (b->save_length) > 5000
--- 5324,5333 ----
                && EMACS_SECS (before_time) - b->auto_save_failure_time < 1200)
              continue;
  
!           set_buffer_internal (b);
!           if (NILP (Vauto_save_include_big_deletions)
!               && (XFASTINT (b->save_length) * 10
!                   > (BUF_Z (b) - BUF_BEG (b)) * 13)
                /* A short file is likely to change a large fraction;
                   spare the user annoying messages.  */
                && XFASTINT (b->save_length) > 5000
***************
*** 5341,5347 ****
                Fsleep_for (make_number (1), Qnil);
                continue;
              }
-           set_buffer_internal (b);
            if (!auto_saved && NILP (no_message))
              message1 ("Auto-saving...");
            internal_condition_case (auto_save_1, Qt, auto_save_error);
--- 5346,5351 ----
***************
*** 5704,5709 ****
--- 5708,5720 ----
  Normally auto-save files are written under other names.  */);
    Vauto_save_visited_file_name = Qnil;
  
+   DEFVAR_LISP ("auto-save-include-big-deletions", 
&Vauto_save_include_big_deletions,
+              doc: /* Non-nil says to auto-save even if a large part of the 
text is deleted.
+ If nil, auto-save is disabled in the buffer if a substantial part of
+ the text is deleted; this is the default, because the auto-save file
+ is usually more useful if it contains the deleted text.  */);
+   Vauto_save_include_big_deletions = Qnil;
+ 
  #ifdef HAVE_FSYNC
    DEFVAR_BOOL ("write-region-inhibit-fsync", &write_region_inhibit_fsync,
               doc: /* *Non-nil means don't call fsync in `write-region'.

Diff finished.  Tue Jul 21 13:45:55 2009